Nearly 800 million people in India lack access to adequate sanitation. The choice of technology for addressing this need may have important sustainability implications. In this study, we used life cycle assessment to compare environmental impacts and nutrient recovery potentials of four different options for providing everyone in India with access to improved sanitation: (i) centralised wastewater treatment with sequential batch reactors (SBR), (ii) twin-pit latrines, (iii) latrines with source separation only and (iv) latrines with source-separation of urine and faeces connected to biogas plants. Results revealed large variability. Closing the sanitation gap through pit latrines would be expected to cause large increases of India's annual greenhouse gas (GHG) emissions, equivalent to 7% of current levels. Source separation only and centralised plants with SBR will be associated with lower GHG emissions, while the biogas scenario shows a potential to provide net emission reduction. The study revealed that source separating systems can provide significant quantities of plant available nitrogen and phosphorus at the country level. Future research should include more technological options and regions. Methodology piloted in this study can be integrated into the planning and design processes for scaling up sanitation in India and other countries.

thank you for sharing your research result with the community!
A question: Was your study limited to certain regions in India or did you consistently work on national level? This might be very helpful, especially for our members and readers who work in India.

Kind regards,
Pelumi on behalf of the SuSanA Secretariat

Posted by a member of the SuSanA secretariat held by the GIZ Sustainable sanitation sector program
Located at Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
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Thanks for posting your paper here. Do you perhaps have a powerpoint presentation to go with it which you could share (since the paper itself is behind a paywall?).

The abstract includes two statements that are not new to us here on this forum but it's always good to have scientific data and evidence for it!
- Closing the sanitation gap through pit latrines would be expected to cause large increases of India's annual greenhouse gas (GHG) emissions, equivalent to 7% of current levels. (what does "equivalent to 7% of current levels" mean? Is that what you mean by "large"?)
- The study revealed that source separating systems can provide significant quantities of plant available nitrogen and phosphorus at the country level.

Do you find that any of your partner organizations in India involved in the SBM drive are paying any attention to the issue of greenhouse gases with pit latrines? As far as I am aware all these new toilets are mainly twin pit pour flush pit latrines which would cause additional greenhouse gas emissions. (SBM is the Clean India Mission, see here:
en.wikipedia.org/wiki/Swachh_Bharat_Abhiyan
)

thanks for sharing the study with us. I agree, that I´ll be helpful to get some more information on the study. It´s sad that it is currently behind a paywall.

Another factor that might be significant as well is the factor of production of the superstructure of these toilets. If the Indian government builds another 10-30 Million toilets, than this factor is significant as well. My personal experience from the current SWM is that most toilets are build from very cheap concrete.

Concrete as a material is harmful as it binds water and sand as two scarce and precious materials forever. The extraction of sand and cement is harmful to the environment and both are non-renewable resources. Production and processing takes a lot of energy along the way. These aspects are hidden CO2 emissions that are included in such a scaled project as well. From my knowledge there is no study that covers that part of LCA so far. Please refer if anybody found one.

Apart from the emission stand point, I think that these toilet houses are as well very alienating in the rural contexts. And my personal standpoint is that they don´t look attractive and I doubt that they will last very long because of the poor-quality. But that is probably a different discussion...

Yes the thinking is right that toilets do look like alienated structures in village landscape and use of cement and sand as materials which require lot of energy for manufacture may not be a good idea considering the carbon emissions point of view.

We have designed a toilet block as a *GREEN ENERGY GENERATING UNIT* where whole thinking is now changed to providing basic livelihood needs of a family in rural and urban area and make the living self sufficient and also add to the income of the family and at the same time include strategies of reducing the carbon foot print.

The toilet block called as *GREEN ENERGY PARK ( Green Kitchen Garden)*will also have herbs and medicinal plants like *Moringa Oleifera *to take care of the health and nutrition of the family.

This way we can totally change our out look for the toilet facility which will look as compact green energy generating unit adding to over all GDP of our country. (Pl see the attached presentation )

It is designed as a *GREEN ENERGY GENERATING UNIT * helping rural communities to become energy independent,rich, healthy and at the same time reducing the carbon foot print. These structures will be eco friendly and will certainly blend nicely with rural setting.

What is the source for 43% of carbon being in urine? This is nearly half, whereas I understand that there is 3 times as much carbon per day in a persons feces than urine.

Producing 169 million toilets will be quite a feat!

To summarise the paper:
The systems studied all have pour flush in common, so use the same amount of water.

GHG emissions were estimated, along with energy used in construction and nutrients recovered.

The results are that:

1. Centralised wastewater treatment plants are energy intensive and nutrients are only recovered from the resulting sludge (I assume the treated wastewater goes into the nearest river)... so by far the highest freshwater eutrophication potential and poor for nutrient recovery.

2. Twin pit latrine lech pits generate huge quantities of methane simply because the decomposition is anaerobic. The sludge is used for agriculture after 3 years. Fairly poor for nutrient recovery. Nitrate leaching potential.

3. Twin pit latrine with source separation allows the diverted urine to be stabilised and used in agriculture separately from the sludge, which is used after 3 years stabilisation. Okay for nutrient recovery. Less GHG emissions from source separation, but still plenty of methane produced by anaerobic decomposition of the soilds.

4. Biogas plant with source separation. These used lots of energy and materials in construction and short lifespan, so there is some global warming potential. Good for nutrient recovery. Practical challenges to wider adoption.

So its horses for courses, nothing standing out as a clear winner. Unless of course they start constructing their pits to be aerobic. Such a simple paradigm shift, to rethink constructing them so they are
shallow and wide
, therefore aerobic. What a huge difference in GHG emissions from such a simple design change.

Or instead of building large wastewater treatment plants that discharge to water bodies and use huge amount of energy to dilute and waste the nutrients, engage in the paradigm shift to low energy aerobic systems, employed at the community or household scale to treat wastewater and discharge to land rather than waterways. To crops for 100% nutrient re-use. Low energy aerobic systems pump wastewater through an aerobic medium rather than air into wastewater, using about 1/10 th of the energy in the process. For an example see this
domestic scale vermifiltration system
that uses less than 5 watts of electricity per person.
cheers
Dean

Apologies for not responding to you, it's been very busy over here. Some replies to your questions below.

Elisabeth:Closing the sanitation gap through pit latrines would be expected to cause large increases of India's annual greenhouse gas (GHG) emissions, equivalent to 7% of current levels. (what does "equivalent to 7% of current levels" mean? Is that what you mean by "large"?)

"current levels" meant all the greenhouse gas emissions of India in 2012 from all sectors and including land use change. The source of data was CAIT climate data explorer by the World Resources Institute.
cait.wri.org
. We called the number large as these are just new toilets alone and it would correspond to for example all the emissions of a small European country, like the Netherlands (from all sectors) .

Kevinkuhn:
The production of superstructure was included in the study (including the supply of concrete and bricks). The impacts are indeed significant (especially in the case of biogas plants), but the main hotspot are still direct methane emissions.

goeco:
The data for molecular content of urine and faeces were derived from the following study:
Rose, C., Parker, A., Jefferson, B., & Cartmell, E. (2015). The characterisation of faeces and urine; a review of the literature to inform advanced treatment technology. Critical Reviews in Environmental Science and Technology
www.ncbi.nlm.nih.gov/pubmed/26246784